The present invention relates to a system and a method of determining a position of a scattering/reflecting element on a surface of a radiation transmissive element, such as on a touch pad.
A number of prior art references relate to this type of technology, such as U.S. Pat. No. 6,504,143, US 20040252091, 2003034439, 20050041013, and 20050073508, WO04/081502 and 04/081956 as well as in KR1060254.
A particular aspect and embodiment of the invention relate to large format displays which are becoming cheaper at an astonishing rate. This has led to a rapid growth in display sizes for different applications such as televisions, monitors etc. and will soon open the market for novel display applications.
Especially monitors are poised to grow and many designers have conceptualized workplaces where monitors and table merge similar to classic drawing tables used by designers and engineers before the digital era. A key property for these workplaces is interactivity and preferably multiple inputs.
Game tables both for home use and for the gaming industry is a similar concept that is on the verge of taking of.
No known technology has provided multiple inputs at a cost comparable to what will be accepted for volume applications.
The present aspect and embodiment do exactly this and do it without impairing the display performance.
Scanning beam above the surface of the display waveguide has been contemplated and MIT has made their laserwall concept public in 1997.
The Laserwall use standard rangefinder technology to determine multiple inputs position. The limiting factor for the design is that the beam once interrupted will not see any objects that are behind the first beam interrupting object. In the concept this shadow interrupt phenomenon is dealt with by using two rangefinders so objects in shadow from one rangefinder will be picked up by the other rangefinder.
According to example embodiments, the determining means may be a processor, such as, described in U.S. Patent Application Publication No. 2003/0137494. For example, the determining means may be a processor configured to determine the position of a scattering/reflecting object based on signals from radiation detectors. In another example, the determining means may be processor in the form of a personal computer configured to execute image analysis software to generate output signals corresponding to user contact with a contact surface of a panel. The determining means may also be a touch controller, which may be implemented in the form of a processor, such as, described in U.S. Patent Application Publication No. 2003/0137494.
In the shadowed areas the resolution will be poorer because there is only one rangefinder available for position detection and this may be more distant. Also position detection cannot be done at all in areas where intersections of shadows occur. Two contaminations right in front of each rangefinder will make the system entirely inoperable. The Laserwall is therefore not a true multiple inputs touch screen. Further the rangefinder will experience touch confirmation problems similar to those associated with classic IR interrupt because the beam may be interrupted prior to actual touch occurs. In the Laserwall concept they have opted for the same approach as for classic IR interrupt where algorithms filter out very brief touches and the optics of both emitter and sensors are designed to irradiate and detect in the closest possible proximity to the touch surface.